With respect to cotton, the level of moisture at harvest through the lint in the bale can have significant effects on the quality of fibre sold to the spinning mill. There are optimum moisture levels for seed-cotton and lint that provide good and efficient ginning, cleaning, baling and safe storage. Likewise there are similar considerations in the processing of other materials and fibres. In the case of moisture, to optimise processing and fibre quality the amount of moisture in a fibre under ambient conditions needs to be balanced with the amount of drying or moisture applied during the various processes.
Despite development of apparatuses that measure and then allow drying or moisture replenishment to be metered onto fibre there has not been widespread uptake due to disadvantages associated with the measurement technique. The main disadvantages of current moisture measurement techniques are their low accuracy and/or that a long time period is required to conduct the tests.
The techniques currently used for measuring the moisture in cotton lint can be classified into five groups. The techniques that are currently used are typically based on either one of:                thermal drying (gravimetric);        chemical reaction analysis;        spectroscopy;        electrical resistance or microwave transmission of water; and        compression and resiliency properties of fibre.        
The use of thermal, chemical and compression methods is excluded from in-line applications on the basis of inadequacy of measurement speed.
Electrical resistance and microwave transmission can be used for in-line applications or in situ. However, both techniques have shortcomings. For instance, resistance meters is carried out using electrode probes that are affected by surface contaminants, which can alter immediate and short-term future readings, and measurements are diminished by very wet or very dry samples, which affect the accuracy of resistance readings. Moreover, resistance apparatuses measure only a small part of the production; hence the problem with contamination of electrodes.
Microwave radiation transmission relies on the sample having a minimum density between the microwave transmitter and antennae. For example, microwave apparatuses are applied very successfully at either end of the cotton ginning process, i.e. to modules of seed-cotton and to compressed bales of cotton lint, where the density of the accumulated fibre is in excess of 100 kg/m3. The application of microwave apparatuses to transport ducts where the density of material is less 15 kg/m3 is considered not viable.
It is an object of the present invention to provide an alternative apparatus and process that can be used to measure, amongst other things, the moisture levels of materials such as fibrous materials.